// Scintilla source code edit control
/** @file LexCSS.cxx
 ** Lexer for Cascading Style Sheets
 ** Written by Jakub Vrna
 ** Improved by Philippe Lhoste (CSS2)
 ** Improved by Ross McKay (SCSS mode; see http://sass-lang.com/ )
 **/
// Copyright 1998-2002 by Neil Hodgson <neilh@scintilla.org>
// The License.txt file describes the conditions under which this software may be distributed.

// TODO: handle SCSS nested properties like font: { weight: bold; size: 1em; }
// TODO: handle SCSS interpolation: #{}
// TODO: add features for Less if somebody feels like contributing; http://lesscss.org/
// TODO: refactor this monster so that the next poor slob can read it!

#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <stdarg.h>
#include <assert.h>
#include <ctype.h>

#include "ILexer.h"
#include "Scintilla.h"
#include "SciLexer.h"

#include "WordList.h"
#include "LexAccessor.h"
#include "Accessor.h"
#include "StyleContext.h"
#include "CharacterSet.h"
#include "LexerModule.h"

#ifdef SCI_NAMESPACE
using namespace Scintilla;
#endif


static inline bool IsAWordChar(const unsigned int ch) {
    /* FIXME:
     * The CSS spec allows "ISO 10646 characters U+00A1 and higher" to be treated as word chars.
     * Unfortunately, we are only getting string bytes here, and not full unicode characters. We cannot guarantee
     * that our byte is between U+0080 - U+00A0 (to return false), so we have to allow all characters U+0080 and higher
     */
    return ch >= 0x80 || isalnum(ch) || ch == '-' || ch == '_';
}

inline bool IsCssOperator(const int ch) {
    if (!((ch < 0x80) && isalnum(ch)) &&
        (ch == '{' || ch == '}' || ch == ':' || ch == ',' || ch == ';' ||
         ch == '.' || ch == '#' || ch == '!' || ch == '@' ||
         /* CSS2 */
         ch == '*' || ch == '>' || ch == '+' || ch == '=' || ch == '~' || ch == '|' ||
         ch == '[' || ch == ']' || ch == '(' || ch == ')')) {
        return true;
    }
    return false;
}

// look behind (from start of document to our start position) to determine current nesting level
inline int NestingLevelLookBehind(unsigned int startPos, Accessor &styler) {
    int ch;
    int nestingLevel = 0;

    for (unsigned int i = 0; i < startPos; i++) {
        ch = styler.SafeGetCharAt(i);
        if (ch == '{')
            nestingLevel++;
        else if (ch == '}')
            nestingLevel--;
    }

    return nestingLevel;
}

static void ColouriseCssDoc(unsigned int startPos, int length, int initStyle, WordList *keywordlists[], Accessor &styler) {
    WordList &css1Props = *keywordlists[0];
    WordList &pseudoClasses = *keywordlists[1];
    WordList &css2Props = *keywordlists[2];
    WordList &css3Props = *keywordlists[3];
    WordList &pseudoElements = *keywordlists[4];
    WordList &exProps = *keywordlists[5];
    WordList &exPseudoClasses = *keywordlists[6];
    WordList &exPseudoElements = *keywordlists[7];

    StyleContext sc(startPos, length, initStyle, styler);

    int lastState = -1; // before operator
    int lastStateC = -1; // before comment
    int lastStateS = -1; // before single-quoted/double-quoted string
    int lastStateVar = -1; // before variable (SCSS)
    int lastStateVal = -1; // before value (SCSS)
    int op = ' '; // last operator
    int opPrev = ' '; // last operator
    bool insideParentheses = false; // true if currently in a CSS url() or similar construct

    // property lexer.css.scss.language
    //	Set to 1 for Sassy CSS (.scss)
    bool isScssDocument = styler.GetPropertyInt("lexer.css.scss.language") != 0;

    // property lexer.css.less.language
    // Set to 1 for Less CSS (.less)
    bool isLessDocument = styler.GetPropertyInt("lexer.css.less.language") != 0;

    // property lexer.css.hss.language
    // Set to 1 for HSS (.hss)
    bool isHssDocument = styler.GetPropertyInt("lexer.css.hss.language") != 0;

    // SCSS/LESS/HSS have the concept of variable
    bool hasVariables = isScssDocument || isLessDocument || isHssDocument;
    char varPrefix = 0;
    if (hasVariables)
        varPrefix = isLessDocument ? '@' : '$';

    // SCSS/LESS/HSS support single-line comments
    typedef enum _CommentModes { eCommentBlock = 0, eCommentLine = 1} CommentMode;
    CommentMode comment_mode = eCommentBlock;
    bool hasSingleLineComments = isScssDocument || isLessDocument || isHssDocument;

    // must keep track of nesting level in document types that support it (SCSS/LESS/HSS)
    bool hasNesting = false;
    int nestingLevel = 0;
    if (isScssDocument || isLessDocument || isHssDocument) {
        hasNesting = true;
        nestingLevel = NestingLevelLookBehind(startPos, styler);
    }

    // "the loop"
    for (; sc.More(); sc.Forward()) {
        if (sc.state == SCE_CSS_COMMENT && ((comment_mode == eCommentBlock && sc.Match('*', '/')) || (comment_mode == eCommentLine && sc.atLineEnd))) {
            if (lastStateC == -1) {
                // backtrack to get last state:
                // comments are like whitespace, so we must return to the previous state
                unsigned int i = startPos;
                for (; i > 0; i--) {
                    if ((lastStateC = styler.StyleAt(i-1)) != SCE_CSS_COMMENT) {
                        if (lastStateC == SCE_CSS_OPERATOR) {
                            op = styler.SafeGetCharAt(i-1);
                            opPrev = styler.SafeGetCharAt(i-2);
                            while (--i) {
                                lastState = styler.StyleAt(i-1);
                                if (lastState != SCE_CSS_OPERATOR && lastState != SCE_CSS_COMMENT)
                                    break;
                            }
                            if (i == 0)
                                lastState = SCE_CSS_DEFAULT;
                        }
                        break;
                    }
                }
                if (i == 0)
                    lastStateC = SCE_CSS_DEFAULT;
            }
            if (comment_mode == eCommentBlock) {
                sc.Forward();
                sc.ForwardSetState(lastStateC);
            } else /* eCommentLine */ {
                sc.SetState(lastStateC);
            }
        }

        if (sc.state == SCE_CSS_COMMENT)
            continue;

        if (sc.state == SCE_CSS_DOUBLESTRING || sc.state == SCE_CSS_SINGLESTRING) {
            if (sc.ch != (sc.state == SCE_CSS_DOUBLESTRING ? '\"' : '\''))
                continue;
            unsigned int i = sc.currentPos;
            while (i && styler[i-1] == '\\')
                i--;
            if ((sc.currentPos - i) % 2 == 1)
                continue;
            sc.ForwardSetState(lastStateS);
        }

        if (sc.state == SCE_CSS_OPERATOR) {
            if (op == ' ') {
                unsigned int i = startPos;
                op = styler.SafeGetCharAt(i-1);
                opPrev = styler.SafeGetCharAt(i-2);
                while (--i) {
                    lastState = styler.StyleAt(i-1);
                    if (lastState != SCE_CSS_OPERATOR && lastState != SCE_CSS_COMMENT)
                        break;
                }
            }
            switch (op) {
                case '@':
                    if (lastState == SCE_CSS_DEFAULT || hasNesting)
                        sc.SetState(SCE_CSS_DIRECTIVE);
                    break;
                case '>':
                case '+':
                    if (lastState == SCE_CSS_TAG || lastState == SCE_CSS_CLASS || lastState == SCE_CSS_ID ||
                        lastState == SCE_CSS_PSEUDOCLASS || lastState == SCE_CSS_EXTENDED_PSEUDOCLASS || lastState == SCE_CSS_UNKNOWN_PSEUDOCLASS)
                        sc.SetState(SCE_CSS_DEFAULT);
                    break;
                case '[':
                    if (lastState == SCE_CSS_TAG || lastState == SCE_CSS_DEFAULT || lastState == SCE_CSS_CLASS || lastState == SCE_CSS_ID ||
                        lastState == SCE_CSS_PSEUDOCLASS || lastState == SCE_CSS_EXTENDED_PSEUDOCLASS || lastState == SCE_CSS_UNKNOWN_PSEUDOCLASS)
                        sc.SetState(SCE_CSS_ATTRIBUTE);
                    break;
                case ']':
                    if (lastState == SCE_CSS_ATTRIBUTE)
                        sc.SetState(SCE_CSS_TAG);
                    break;
                case '{':
                    nestingLevel++;
                    switch (lastState) {
                        case SCE_CSS_MEDIA:
                            sc.SetState(SCE_CSS_DEFAULT);
                            break;
                        case SCE_CSS_TAG:
                        case SCE_CSS_DIRECTIVE:
                            sc.SetState(SCE_CSS_IDENTIFIER);
                            break;
                    }
                    break;
                case '}':
                    if (--nestingLevel < 0)
                        nestingLevel = 0;
                    switch (lastState) {
                        case SCE_CSS_DEFAULT:
                        case SCE_CSS_VALUE:
                        case SCE_CSS_IMPORTANT:
                        case SCE_CSS_IDENTIFIER:
                        case SCE_CSS_IDENTIFIER2:
                        case SCE_CSS_IDENTIFIER3:
                            if (hasNesting)
                                sc.SetState(nestingLevel > 0 ? SCE_CSS_IDENTIFIER : SCE_CSS_DEFAULT);
                            else
                                sc.SetState(SCE_CSS_DEFAULT);
                            break;
                    }
                    break;
                case '(':
                    if (lastState == SCE_CSS_PSEUDOCLASS)
                        sc.SetState(SCE_CSS_TAG);
                    else if (lastState == SCE_CSS_EXTENDED_PSEUDOCLASS)
                        sc.SetState(SCE_CSS_EXTENDED_PSEUDOCLASS);
                    break;
                case ')':
                    if (lastState == SCE_CSS_TAG || lastState == SCE_CSS_DEFAULT || lastState == SCE_CSS_CLASS || lastState == SCE_CSS_ID ||
                        lastState == SCE_CSS_PSEUDOCLASS || lastState == SCE_CSS_EXTENDED_PSEUDOCLASS || lastState == SCE_CSS_UNKNOWN_PSEUDOCLASS ||
                        lastState == SCE_CSS_PSEUDOELEMENT || lastState == SCE_CSS_EXTENDED_PSEUDOELEMENT)
                        sc.SetState(SCE_CSS_TAG);
                    break;
                case ':':
                    switch (lastState) {
                        case SCE_CSS_TAG:
                        case SCE_CSS_DEFAULT:
                        case SCE_CSS_CLASS:
                        case SCE_CSS_ID:
                        case SCE_CSS_PSEUDOCLASS:
                        case SCE_CSS_EXTENDED_PSEUDOCLASS:
                        case SCE_CSS_UNKNOWN_PSEUDOCLASS:
                        case SCE_CSS_PSEUDOELEMENT:
                        case SCE_CSS_EXTENDED_PSEUDOELEMENT:
                            sc.SetState(SCE_CSS_PSEUDOCLASS);
                            break;
                        case SCE_CSS_IDENTIFIER:
                        case SCE_CSS_IDENTIFIER2:
                        case SCE_CSS_IDENTIFIER3:
                        case SCE_CSS_EXTENDED_IDENTIFIER:
                        case SCE_CSS_UNKNOWN_IDENTIFIER:
                        case SCE_CSS_VARIABLE:
                            sc.SetState(SCE_CSS_VALUE);
                            lastStateVal = lastState;
                            break;
                    }
                    break;
                case '.':
                    if (lastState == SCE_CSS_TAG || lastState == SCE_CSS_DEFAULT || lastState == SCE_CSS_CLASS || lastState == SCE_CSS_ID ||
                        lastState == SCE_CSS_PSEUDOCLASS || lastState == SCE_CSS_EXTENDED_PSEUDOCLASS || lastState == SCE_CSS_UNKNOWN_PSEUDOCLASS)
                        sc.SetState(SCE_CSS_CLASS);
                    break;
                case '#':
                    if (lastState == SCE_CSS_TAG || lastState == SCE_CSS_DEFAULT || lastState == SCE_CSS_CLASS || lastState == SCE_CSS_ID ||
                        lastState == SCE_CSS_PSEUDOCLASS || lastState == SCE_CSS_EXTENDED_PSEUDOCLASS || lastState == SCE_CSS_UNKNOWN_PSEUDOCLASS)
                        sc.SetState(SCE_CSS_ID);
                    break;
                case ',':
                case '|':
                case '~':
                    if (lastState == SCE_CSS_TAG)
                        sc.SetState(SCE_CSS_DEFAULT);
                    break;
                case ';':
                    switch (lastState) {
                        case SCE_CSS_DIRECTIVE:
                            if (hasNesting) {
                                sc.SetState(nestingLevel > 0 ? SCE_CSS_IDENTIFIER : SCE_CSS_DEFAULT);
                            } else {
                                sc.SetState(SCE_CSS_DEFAULT);
                            }
                            break;
                        case SCE_CSS_VALUE:
                        case SCE_CSS_IMPORTANT:
                            // data URLs can have semicolons; simplistically check for wrapping parentheses and move along
                            if (insideParentheses) {
                                sc.SetState(lastState);
                            } else {
                                if (lastStateVal == SCE_CSS_VARIABLE) {
                                    sc.SetState(SCE_CSS_DEFAULT);
                                } else {
                                    sc.SetState(SCE_CSS_IDENTIFIER);
                                }
                            }
                            break;
                        case SCE_CSS_VARIABLE:
                            if (lastStateVar == SCE_CSS_VALUE) {
                                // data URLs can have semicolons; simplistically check for wrapping parentheses and move along
                                if (insideParentheses) {
                                    sc.SetState(SCE_CSS_VALUE);
                                } else {
                                    sc.SetState(SCE_CSS_IDENTIFIER);
                                }
                            } else {
                                sc.SetState(SCE_CSS_DEFAULT);
                            }
                            break;
                    }
                    break;
                case '!':
                    if (lastState == SCE_CSS_VALUE)
                        sc.SetState(SCE_CSS_IMPORTANT);
                    break;
            }
        }

        if (sc.ch == '*' && sc.state == SCE_CSS_DEFAULT) {
            sc.SetState(SCE_CSS_TAG);
            continue;
        }

        // check for inside parentheses (whether part of an "operator" or not)
        if (sc.ch == '(')
            insideParentheses = true;
        else if (sc.ch == ')')
            insideParentheses = false;

        // SCSS special modes
        if (hasVariables) {
            // variable name
            if (sc.ch == varPrefix) {
                switch (sc.state) {
                    case SCE_CSS_DEFAULT:
                        if (isLessDocument) // give priority to pseudo elements
                            break;
                    case SCE_CSS_VALUE:
                        lastStateVar = sc.state;
                        sc.SetState(SCE_CSS_VARIABLE);
                        continue;
                }
            }
            if (sc.state == SCE_CSS_VARIABLE) {
                if (IsAWordChar(sc.ch)) {
                    // still looking at the variable name
                    continue;
                }
                if (lastStateVar == SCE_CSS_VALUE) {
                    // not looking at the variable name any more, and it was part of a value
                    sc.SetState(SCE_CSS_VALUE);
                }
            }

            // nested rule parent selector
            if (sc.ch == '&') {
                switch (sc.state) {
                    case SCE_CSS_DEFAULT:
                    case SCE_CSS_IDENTIFIER:
                        sc.SetState(SCE_CSS_TAG);
                        continue;
                }
            }
        }

        // nesting rules that apply to SCSS and Less
        if (hasNesting) {
            // check for nested rule selector
            if (sc.state == SCE_CSS_IDENTIFIER && (IsAWordChar(sc.ch) || sc.ch == ':' || sc.ch == '.' || sc.ch == '#')) {
                // look ahead to see whether { comes before next ; and }
                unsigned int endPos = startPos + length;
                int ch;

                for (unsigned int i = sc.currentPos; i < endPos; i++) {
                    ch = styler.SafeGetCharAt(i);
                    if (ch == ';' || ch == '}')
                        break;
                    if (ch == '{') {
                        sc.SetState(SCE_CSS_DEFAULT);
                        continue;
                    }
                }
            }

        }

        if (IsAWordChar(sc.ch)) {
            if (sc.state == SCE_CSS_DEFAULT)
                sc.SetState(SCE_CSS_TAG);
            continue;
        }

        if (IsAWordChar(sc.chPrev) && (
                sc.state == SCE_CSS_IDENTIFIER || sc.state == SCE_CSS_IDENTIFIER2 ||
                sc.state == SCE_CSS_IDENTIFIER3 || sc.state == SCE_CSS_EXTENDED_IDENTIFIER ||
                sc.state == SCE_CSS_UNKNOWN_IDENTIFIER ||
                sc.state == SCE_CSS_PSEUDOCLASS || sc.state == SCE_CSS_PSEUDOELEMENT ||
                sc.state == SCE_CSS_EXTENDED_PSEUDOCLASS || sc.state == SCE_CSS_EXTENDED_PSEUDOELEMENT ||
                sc.state == SCE_CSS_UNKNOWN_PSEUDOCLASS ||
                sc.state == SCE_CSS_IMPORTANT ||
                sc.state == SCE_CSS_DIRECTIVE
        )) {
            char s[100];
            sc.GetCurrentLowered(s, sizeof(s));
            char *s2 = s;
            while (*s2 && !IsAWordChar(*s2))
                s2++;
            switch (sc.state) {
                case SCE_CSS_IDENTIFIER:
                case SCE_CSS_IDENTIFIER2:
                case SCE_CSS_IDENTIFIER3:
                case SCE_CSS_EXTENDED_IDENTIFIER:
                case SCE_CSS_UNKNOWN_IDENTIFIER:
                    if (css1Props.InList(s2))
                        sc.ChangeState(SCE_CSS_IDENTIFIER);
                    else if (css2Props.InList(s2))
                        sc.ChangeState(SCE_CSS_IDENTIFIER2);
                    else if (css3Props.InList(s2))
                        sc.ChangeState(SCE_CSS_IDENTIFIER3);
                    else if (exProps.InList(s2))
                        sc.ChangeState(SCE_CSS_EXTENDED_IDENTIFIER);
                    else
                        sc.ChangeState(SCE_CSS_UNKNOWN_IDENTIFIER);
                    break;
                case SCE_CSS_PSEUDOCLASS:
                case SCE_CSS_PSEUDOELEMENT:
                case SCE_CSS_EXTENDED_PSEUDOCLASS:
                case SCE_CSS_EXTENDED_PSEUDOELEMENT:
                case SCE_CSS_UNKNOWN_PSEUDOCLASS:
                    if (op == ':' && opPrev != ':' && pseudoClasses.InList(s2))
                        sc.ChangeState(SCE_CSS_PSEUDOCLASS);
                    else if (opPrev == ':' && pseudoElements.InList(s2))
                        sc.ChangeState(SCE_CSS_PSEUDOELEMENT);
                    else if ((op == ':' || (op == '(' && lastState == SCE_CSS_EXTENDED_PSEUDOCLASS)) && opPrev != ':' && exPseudoClasses.InList(s2))
                        sc.ChangeState(SCE_CSS_EXTENDED_PSEUDOCLASS);
                    else if (opPrev == ':' && exPseudoElements.InList(s2))
                        sc.ChangeState(SCE_CSS_EXTENDED_PSEUDOELEMENT);
                    else
                        sc.ChangeState(SCE_CSS_UNKNOWN_PSEUDOCLASS);
                    break;
                case SCE_CSS_IMPORTANT:
                    if (strcmp(s2, "important") != 0)
                        sc.ChangeState(SCE_CSS_VALUE);
                    break;
                case SCE_CSS_DIRECTIVE:
                    if (op == '@' && strcmp(s2, "media") == 0)
                        sc.ChangeState(SCE_CSS_MEDIA);
                    break;
            }
        }

        if (sc.ch != '.' && sc.ch != ':' && sc.ch != '#' && (
                sc.state == SCE_CSS_CLASS || sc.state == SCE_CSS_ID ||
                (sc.ch != '(' && sc.ch != ')' && ( /* This line of the condition makes it possible to extend pseudo-classes with parentheses */
                        sc.state == SCE_CSS_PSEUDOCLASS || sc.state == SCE_CSS_PSEUDOELEMENT ||
                        sc.state == SCE_CSS_EXTENDED_PSEUDOCLASS || sc.state == SCE_CSS_EXTENDED_PSEUDOELEMENT ||
                        sc.state == SCE_CSS_UNKNOWN_PSEUDOCLASS
                ))
        ))
            sc.SetState(SCE_CSS_TAG);

        if (sc.Match('/', '*')) {
            lastStateC = sc.state;
            comment_mode = eCommentBlock;
            sc.SetState(SCE_CSS_COMMENT);
            sc.Forward();
        } else if (hasSingleLineComments && sc.Match('/', '/') && !insideParentheses) {
            // note that we've had to treat ([...]// as the start of a URL not a comment, e.g. url(http://example.com), url(//example.com)
            lastStateC = sc.state;
            comment_mode = eCommentLine;
            sc.SetState(SCE_CSS_COMMENT);
            sc.Forward();
        } else if ((sc.state == SCE_CSS_VALUE || sc.state == SCE_CSS_ATTRIBUTE)
                   && (sc.ch == '\"' || sc.ch == '\'')) {
            lastStateS = sc.state;
            sc.SetState((sc.ch == '\"' ? SCE_CSS_DOUBLESTRING : SCE_CSS_SINGLESTRING));
        } else if (IsCssOperator(sc.ch)
                   && (sc.state != SCE_CSS_ATTRIBUTE || sc.ch == ']')
                   && (sc.state != SCE_CSS_VALUE || sc.ch == ';' || sc.ch == '}' || sc.ch == '!')
                   && ((sc.state != SCE_CSS_DIRECTIVE && sc.state != SCE_CSS_MEDIA) || sc.ch == ';' || sc.ch == '{')
                ) {
            if (sc.state != SCE_CSS_OPERATOR)
                lastState = sc.state;
            sc.SetState(SCE_CSS_OPERATOR);
            op = sc.ch;
            opPrev = sc.chPrev;
        }
    }

    sc.Complete();
}

static void FoldCSSDoc(unsigned int startPos, int length, int, WordList *[], Accessor &styler) {
    bool foldComment = styler.GetPropertyInt("fold.comment") != 0;
    bool foldCompact = styler.GetPropertyInt("fold.compact", 1) != 0;
    unsigned int endPos = startPos + length;
    int visibleChars = 0;
    int lineCurrent = styler.GetLine(startPos);
    int levelPrev = styler.LevelAt(lineCurrent) & SC_FOLDLEVELNUMBERMASK;
    int levelCurrent = levelPrev;
    char chNext = styler[startPos];
    bool inComment = (styler.StyleAt(startPos-1) == SCE_CSS_COMMENT);
    for (unsigned int i = startPos; i < endPos; i++) {
        char ch = chNext;
        chNext = styler.SafeGetCharAt(i + 1);
        int style = styler.StyleAt(i);
        bool atEOL = (ch == '\r' && chNext != '\n') || (ch == '\n');
        if (foldComment) {
            if (!inComment && (style == SCE_CSS_COMMENT))
                levelCurrent++;
            else if (inComment && (style != SCE_CSS_COMMENT))
                levelCurrent--;
            inComment = (style == SCE_CSS_COMMENT);
        }
        if (style == SCE_CSS_OPERATOR) {
            if (ch == '{') {
                levelCurrent++;
            } else if (ch == '}') {
                levelCurrent--;
            }
        }
        if (atEOL) {
            int lev = levelPrev;
            if (visibleChars == 0 && foldCompact)
                lev |= SC_FOLDLEVELWHITEFLAG;
            if ((levelCurrent > levelPrev) && (visibleChars > 0))
                lev |= SC_FOLDLEVELHEADERFLAG;
            if (lev != styler.LevelAt(lineCurrent)) {
                styler.SetLevel(lineCurrent, lev);
            }
            lineCurrent++;
            levelPrev = levelCurrent;
            visibleChars = 0;
        }
        if (!isspacechar(ch))
            visibleChars++;
    }
    // Fill in the real level of the next line, keeping the current flags as they will be filled in later
    int flagsNext = styler.LevelAt(lineCurrent) & ~SC_FOLDLEVELNUMBERMASK;
    styler.SetLevel(lineCurrent, levelPrev | flagsNext);
}

static const char * const cssWordListDesc[] = {
        "CSS1 Properties",
        "Pseudo-classes",
        "CSS2 Properties",
        "CSS3 Properties",
        "Pseudo-elements",
        "Browser-Specific CSS Properties",
        "Browser-Specific Pseudo-classes",
        "Browser-Specific Pseudo-elements",
        0
};

LexerModule lmCss(SCLEX_CSS, ColouriseCssDoc, "css", FoldCSSDoc, cssWordListDesc);
